This invention relates to the use of a source of dietary lipids for the preparation of a food composition intended for improving or maintaining the skin health and/or coat quality in a pet by regulating the level of the anti-microbial fatty acids in the epidermis of animal. The invention also relates to a method for improving skin health and/or coat quality in a pet, and the petfood formulation thereon.
Skin is the outer boundary of the body, and plays a key role as a barrier between a living organism and the environment. One of the most important functions of the skin is to retain water and hydrosoluble compounds from leaving or entering the body. Impaired barrier function of the skin may lead to e.g., increased susceptibility to skin infections, inflammation, itching.
Most of the barrier function of the skin is provided by the outer layer of the epidermis, the stratum corneum. It consists mainly of layers of keratinocytes which die as they progress towards the surface and are shed. The stratum corneum contains lipids which help maintain the cohesion between the keratinocytes, thus ensuring the waterproofing of the epidermis.
There are several situations when the barrier function of the skin is adequate under normal conditions, but becomes insufficient due to changes in physiological, environmental, or pathological conditions. The skin generally adapts to those conditions by increasing the synthesis of skin lipids: triglycerides, cholesterol and cholesterol esters, ceramides (Grubauer et al, 1987, Journal of Lipid Research 1987; 28 (6): 746-752). This process allows the skin to reach an adequate level of protection after about 48 hours.
Nutrition may impact skin barrier function. The international patent application WO 9856263 discloses the combination of linoleic acid and zinc for the improvement of skin quality and coat condition in pets, for example.
Another aspect by which nutrition may impact the skin is through fatty acids might inhibit the development of inflammatory reactions on the skin, e.g., the fatty acid a-linolenic (Vaughn DM et al, 1994, Vet. Dermatol. 5: 163-173).
It is known that skin lipids, and more specifically, free fatty acids can be anti-microbial to Gram-positive pathogenic bacteria (Bibel D. J. et al., 1989, J. Invest. Dermatol, 92, 632-638). In particular, palmitoleic and lauric acids are known for their anti-microbial activity against common skin pathogens from in vitro studies. Indeed, lauric acid, palmitoleic acid or linoleic acid were shown inhibitory in vitro against several skin pathogens such as Pneumococci, Streptococcus, Corynebacteria, Micrococci, Candida, Staphylococcus aureus (Kabara et al., 1972, Antimicro. Agents and Chemo., 2, 23-28 and, 1978, J. Soc. Cosmet. Chem., 29, 733-741).
However, there is no data on the effect of nutritionally induced increased concentration of such fatty acids for an increased protection against pathogens growth, i.e. increasing the level of antimicrobial fatty acids in the epidermis or the skin by nutrition.